Jens Stoltenberg will wrap up a NATO summit for a final time at the helm

BRUSSELS (AP) — Jens Stoltenberg will bid farewell to NATO leaders on Thursday after chairing his final summit as the military alliance’s top civilian official, bringing an unofficial end to a decade at the helm during one of the most tumultuous periods in its history.

Stoltenberg steps down as NATO’s 13th secretary-general in the fall, handing over to former Dutch Prime Minister Mark Rutte on Oct. 1. Only Joseph Luns, who spent 12 years in charge, was head of the world's biggest security organization for longer.

Stoltenberg took over in 2014, the year that “ little green men ” from Russia infiltrated Ukraine. Moscow annexed the Crimean Peninsula, awakening NATO from a post-Cold War slumber. So began a defense spending buildup that gathered momentum throughout his term.

Over the past decade, the 65-year-old former Norwegian prime minister built a reputation as diplomatically astute, and he ran a tight ship at NATO headquarters in Brussels, ruffling feathers at times among some national delegations.

But his affable nature, mixing serious high politics with bright humor, won him many supporters.

“I like the Washington Treaty,” Stoltenberg has said of NATO’s founding text in somewhat teacherly tones, before pausing a beat. “Not least because it is very short.” At the end of one interview, he smiled and told an Associated Press team: “We still have time for jokes.”

In awarding him the Presidential Medal of Freedom on Tuesday, President Joe Biden praised Stoltenberg as “a man of integrity and intellectual rigor, a calm temperament in a moment of crisis, a consummate diplomat who works with leaders across the political spectrum and always finds a way to keep us moving forward.”

Biden said he had steered NATO “through one of the most consequential periods in its history.”

The Stoltenberg decade was marked early by a failed military coup in NATO ally Turkey in 2016. He rallied quickly to President Recep Tayyip Erdogan’s side, establishing political capital that would serve him well later with Turkey’s proud and sometimes unpredictable leader.

As hundreds of Turkish military personnel — including officers who had won the respect of their allies — were purged at NATO, the charges against them opaque at best, Stoltenberg remained mostly silent, at least in public.

The same year, as he was preparing NATO’s complex move into a sprawling new headquarters, Donald Trump was elected president of the alliance’s most powerful member country — “the chairman of the board,” in the words of one senior European NATO diplomat.

Trump’s bluster about allies owing America money undermined trust among the members. NATO’s guideline to spend 2% of gross domestic product on defense was a target that concerned national budgets only, not any common funding that might require a country to pay dues.

It became an existential challenge. Smaller members feared that the U.S. under Trump would renege on NATO’s security pledge that all countries must to come to the rescue of any ally in trouble, the foundation the alliance is built on.

During the Trump era, Foreign Policy magazine named Stoltenberg diplomat of the year in 2019 “for his exceptional direction at a time of uncertainty regarding NATO’s future.” Many NATO diplomats praised his political acumen. Some rankled at his indulgence of Trump.

But Stoltenberg had little influence in 2021, when Biden made good on Trump’s promise to pull U.S. troops out of Afghanistan. That's where NATO ran its biggest and most challenging security operation ever for almost two decades. The Taliban seized back power, humiliating the allies.

Russian President Vladimir Putin’s invasion of Ukraine in 2022 shook NATO out of its torpor. The alliance was formed 75 years ago to confront the Soviet Union, and it was back in its element. Stoltenberg drove the joint response to the war, pushing NATO to repeat its 2008 promise that Ukraine should join one day.

He was a major backer of Finland and Sweden when they decided to join NATO.

But Ukraine’s membership remains a distant prospect, with the war in its third year, and the bombing of its largest children’s hospital on the eve of the summit is a stark reminder that Putin is unlikely to seek peace soon.

Hungarian Prime Minister Viktor Orban’s uncoordinated “peacemaking” trips to Kyiv, Moscow and Beijing is also a reminder of the nationalist populism that lurks within NATO’s ranks and threatens to undermine its unity. He was due to meet Thursday with Trump at his beachside compound Mar-a-Lago following the NATO summit.

Rutte has plenty to do, and Stoltenberg is a difficult man to replace. His term was renewed several times over his decade in office, in part to keep a firm hand on the tiller during the war but also because the allies could not agree on a replacement.

Despite all its challenges, he believes that NATO will survive, regardless of who wins the U.S. elections in November.

“We cannot take it for granted. It’s not a given. It was not a given in 1949,” Stoltenberg said. “But the reality is that we have a strong common interest in standing together. So, therefore, I’m optimistic for the future of this alliance.”

As for what's next, Stoltenberg had hoped to take up a job at the head of Norway’s central bank at one point. He mulled his future again this week, after throwing the opening pitch to mark the start of a Washington National’s baseball game, and he has already ruled out one line of work.

“That is the most difficult thing I have ever done as NATO secretary-general,” he said, conceding that the baseball itself was not what he had expected. “I thought it was a tennis ball, but it’s not the case. So it was a very steep learning curve, and I think my future is not in baseball.”